Soldering thread

[Seoul_lasers]

I'm not really sure, at some time gas powered soldering irons were promoted as suitable for electronics here. These were very small ones though, not suitable for large gauge wires at all.

To me they are mostly fieldwork things, if you have no power available you can resort to using them, probably to restore the power in the first place


As for proper soldering solutions go: Don't spend a lot on them if you are just starting up. Things like the really cheap Aoyue soldering stations are actually not that bad as long as you get the proper tips for them.

The smaller chisel shaped bits that come for those are actually pretty good for general electronics work, and could be used to solder laser diodes easily.

Things like solder suckers or smd tweezers are nice, but not required for general assembly work. You don't need them to remove defective components either, but you might when you want to remove non-defective components for re-purposing or something like that.

Those vacuum solder suckers are good for very fast desoldering and repurposing components. Removing ribbon cables from Laser diodes is super simple and very safe with them.
I tried doing an open can from a LG 20x RW (LPC-826) with one last October and got all the solder off in one go barely subjecting the diode to any heating, just to see if I could do it. (it was a dead drive)
I ended up building it into an Aluminum press fit module and giving it to a classmate.

 

[Benm]

That's not someting very hard to do though. You could just flow some proper flux core solder onto the flex and rip it off in one go - i've done it before without any problems or damage to the laser diode.

To be honest i have no idea on how hot the laser diode chip got during that, but at least it was not damaged at all. Clamping down the case may also aid taking some heat away if required.

Then again it's not like laser diodes are that sensitive to heat at all when not operating. Heating them up to temperatures that melt proper solder is usually no problem when not powered as long as you work quickly (in 10 seconds or so). And even that is just datasheet guarantees, they may survive much more thermal abuse in practical situations.

I haven't really tried this on laser diodes, but i've had cmos chips and such at far higher temperatures for far to long without damage at all (thing of DIP16 package desoldering using a paint stripper) - obviously under unpowered conditions.

 

[Seoul_lasers]

That's not someting very hard to do though. You could just flow some proper flux core solder onto the flex and rip it off in one go - i've done it before without any problems or damage to the laser diode.

To be honest i have no idea on how hot the laser diode chip got during that, but at least it was not damaged at all. Clamping down the case may also aid taking some heat away if required.

Then again it's not like laser diodes are that sensitive to heat at all when not operating. Heating them up to temperatures that melt proper solder is usually no problem when not powered as long as you work quickly (in 10 seconds or so). And even that is just datasheet guarantees, they may survive much more thermal abuse in practical situations.

I haven't really tried this on laser diodes, but i've had cmos chips and such at far higher temperatures for far to long without damage at all (thing of DIP16 package desoldering using a paint stripper) - obviously under unpowered conditions.

Most of those Laser diodes do not like to be at elevated temps for very long and get quite tempermental even when not in service (bridge wires and cavity mirrors). At any rate a vacuum solder sucker is the most ideal way of removing solder (fastest). If you can afford one of those, I'd get one. Better than fighting with solder braid and safer.

 

[Benm]

I don't use desoldering braid to get the flex off of diodes at all, just melt all the connections at once with leaded solder. Once liquid just pull it away and it will take most solder with it as you go.

For thermal management it woud be best to have the actual diode case in a vise or similarly large thermal mass to provide adequate cooling. Then again ripping off the flex takes only a second or two with molten solder, probably within the manufacturers thermal profile.

For people new to soldering the only thing i can really recommend is gaining experience. Get some cheapass kits to solder and desolder, and don't worry about destroying something in the process.

Soldering technique is a mostly practical skill. It's not something overly difficult to master at all, but it does take some time and effort. Just get a couple of chinese clock kits and build those, take them apart again etc to get the feel for it.

You might destroy some components in that process, could burn your fingers a couple of times and what not. You will get better at it very quickly though.

 

[Seoul_lasers]

I don't use desoldering braid to get the flex off of diodes at all, just melt all the connections at once with leaded solder. Once liquid just pull it away and it will take most solder with it as you go.

For thermal management it woud be best to have the actual diode case in a vise or similarly large thermal mass to provide adequate cooling. Then again ripping off the flex takes only a second or two with molten solder, probably within the manufacturers thermal profile.

For people new to soldering the only thing i can really recommend is gaining experience. Get some cheapass kits to solder and desolder, and don't worry about destroying something in the process.

Soldering technique is a mostly practical skill. It's not something overly difficult to master at all, but it does take some time and effort. Just get a couple of chinese clock kits and build those, take them apart again etc to get the feel for it.

You might destroy some components in that process, could burn your fingers a couple of times and what not. You will get better at it very quickly though.

Good point... I'm lazy, and prefer solder suckers. I'm addicted to using them as they do such an incredible job. I rather not have to apply much heat to remove solder if I can help it.

 

[Benm]

I understand... but looking at datasheets many components can actually tolerate quite a bit of heat over some time when not active. Those figures are also guaranteed ratings, practical survival is often much longer.

For most small packages it really isn't a problem at all, though for larger ones with many pins it can become one.

Then again, how often do you actually remove something like a 40 pin chip when it's not defective already?

 

[Seoul_lasers]

I understand... but looking at datasheets many components can actually tolerate quite a bit of heat over some time when not active. Those figures are also guaranteed ratings, practical survival is often much longer.

For most small packages it really isn't a problem at all, though for larger ones with many pins it can become one.

Then again, how often do you actually remove something like a 40 pin chip when it's not defective already?

True enough... Though I would tend to lean more to "the smaller the package the easier it is to overheat." rather than the reverse. The larger the item the greater the thermal mass.

Back to my point,

There is some decent literature on LDs pointing to heating, even while not powered causing micro flaws in the n/p type semiconductor material which can result in catastrophic facet damage
(CFD) a condition resulting in a melting of the mirror facet/ or facet coating thus resulting in a laser diode that undergoes a complete thermal runaway when powered up... and a LED'ed diode.

These can (CFDs) be caused by ESD, thermal shock, reflected laser light ( resulting in cavity re-absorption), too much current... as well as environmental factors including excessive heat (as in soldering).

This is why one must be super careful when desoldering a LD ribbon cable.

I have put a link into this post that many of you will really find interesting.
by ILX Lightwave. Newport Co.

http://assets.newport.com/webDocuments-EN/images/AN03_Protecting_Laser_Diode_IX.pdf

 

[Benm]

Causing small defects in the facets due to overheating (or mechanical stress, esd, etc) can indeed cause COD later.

Most laser diodes are however rated to be at 175C for 10 seconds or something in that order when being soldered.

The safest way to ensure the diode does not get that hot at all is actually to have it gripped in a vise or something similar that makes good thermal contact and has considerable thermal mass.

Doing so ensures you can heat up the pins pretty hot without the actual diode getting overheated. This is especially useful in case-neutral devices where there is no direct connection between pins and body. If there is a pin connected to the body that serves no electrical function, just clip that instead of desoldering as you don't need it anyway.

You do need to be careful about ESD with such devices though.

 

[Sterling532]

Awhile back Sterling Resale Optics had a deal with Sam's Laser FAQ to supply indium foil and low temp soLder at cost to those building DPSS lasers. I exhausted my bulk supply of foil and soLder but have about a pint of Indalloy #5-RMA-RC amber rosin flux. It still appears ok. My QUESTION: after being stored in a basement for a decade would you still use it or is it "expired"? Thanks for your advice from a non-soLderer.

 

[djQUAN]

Not sure if it has been mentioned before, get decent quality 63/37 eutectic solder rather than the old 60/40 blend. It results to much better looking joints.

I had been using the old 30W cheap irons for years, stepped up to a cheap 60W temp controlled pencil (controller built into the handle but still bulky) then later got a Hakko 888 and eventually a FX951. Still using both stations fitted with different tips.

To those that say you don't need a station, a cheap iron is plenty... Don't knock it until you've tried it. even a cheap clone temp controlled station is loads better than a pencil iron. Thinking of getting a TS100 as online reviews put it close to my 951 in performance but planning it for portable use. There is also a good selection of tip types.

I also used a spring type sucker from Goot which works well but then got a Hakko FR300. Pricey but removing parts from multilayer boards is very easy. Parts simply fall off without damage to the PCB, but it is quite pricey and beyond most hobbyist budgets.

 

[djQUAN]

I have never heard of flux having an expiration date, I doubt it goes bad, anyone?

I have quality solders that have expiry dates of about 2years from manufacture. It has something to do that the manufacturer can guarantee effectivity of the flux in wetting oxidized components.

Although I have used ones that seem to work fine well past its "use by" date, I also noticed some quality old solders I have used before have a little harder time wetting oxidized parts compared to newer stock.

 

[paul1598419]

I have never heard of rosin flux going bad if it is separate from the solder, but I don't still have anything that old left. My oldest solder with a rosin core is about 2 years old.

 

[Benm]

I'm not sure if it -ever- goes bad, but i've used rosin core tin/lead solder that was definitely over 10 years old without any problems. This is the good old 60/40 or 63/37 solder though, maybe flux in newer lead free solders does go bad sooner.

Als 60/40 or 63/37 are concerned, i'm not sure they are actually much different. The latter ratio is the exact eutectic ratio for tin and lead, but when you solder on component leads you are likely to get other metals in the solder joint as well. This could be extra tin from component leads that are sometimes covered in pure tin, but also copper from the leads and circuit board that dissolves a little bit.

In the last decade or so i've noticed that they use cheaper materials for through hole component leads: i've had some resistors where their legs actually stuck to a magnet. This would definitely never happed with a tinned copper lead.

I'm not exactly sure what those leads are made off, but the magnetic attraction is fairly strong so i presume something ferromagnetic, like galvanized or tinned steel. It looks like it's coated in tin or perhaps zinc, either would allow normal solder to wet the surface.

I've checked some other components for this magnetic property in the leads as well, but did not find many older components that stuck to magnets by their leads, with the exception of some pretty simple 5mm type LED's that must have been from the 90s.

They solder in just fine though, i just though i should mention this because those ferromagnetic metals may also mess with the composition of the final solder joint.

 

[paul1598419]

That is disturbing information. I have never heard of component leads made of ferrous metals before. I will have to check all my resistors and capacitors to see if any are like what you have found. That is pure crap and only what I would expect to see in China. But, ferrous metals are often more brittle than copper, so I rather doubt mine are magnetic. I will check, however.

 

[badboybilly]

Anyone now we’re to get the awsome flux in a syringe that Jeff used to sell!

 

[djQUAN]

That is disturbing information. I have never heard of component leads made of ferrous metals before.

All Electrolytics have steel leads, even the older ones. Most LED leadframes are steel. They corrode and rust when wet in those christmas lights used outdoors.

I have compared 60/40 and 63/37 and the difference is clear. I only use 63/37 in all my projects or sometimes the 62/36/2 with silver for silver plated contacts.

steel leads in axial resistors are fairly recent (a few years or so) but mostly in cheap ones. branded ones still have copper leads. Copper leaded electrolytics also exist but mostly in premium "audio grade" variants because audiophiles could "hear" the difference and steel affects the sound.